Hypodermic injector



D. S. LOVE HYPODERMIC INJECTOR May 5, 1964 3 Sheets-Sheet 1 Filed March 14. 1961 Fly. .5.

y 5, 1954 D. s. LOVE 3,131,692

' HYPODERMIC INJECTOR Filed March 14, 1961 3 Sheets-Sheet 2 3 Sheets-Sheet 5 y 1964 D. 5. LOVE HYPODERMIC INJECTOR Filed March 14. 1961 C 4 62 M 4 g 2 \K 1 A|1. 1 w MU MU m uh .I HI. 0 2 PM x A w 4 3 2 2 2 Z a 3 2 2% 2 8 w W 2 w m? v h a 3 United States Patent 3,131,692 HYPGDERMIC INEECTGR Douglas Stanley Love, Thornton Heath, England, assignor to Express liniector Co., Ltd., London, England Filed Mar. 14, 1961, Ser. No. 95,718 Claims priority, application Great Britain Mar. 23, 1%0 4 Claims. (til. 128-4173) The invention relates to an improved hypodermic injector of the kind capable of discharging a jet of liquid through the skin of a patient without the use of a hypodermic needle. Such injectors are adapted to be fitted with an ampoule or container for liquid medicament and it has been proposed heretofore to expel the medicament from a discharge orifice in one end of the ampoule by a piston or follower which is forced down the ampoule by a spring operated plunger. It has also been proposed to discharge medicament from an ampoule in two pressure stages and to this end the said piston which expels the medicament from the ampoule has been formed of flexible material the arrangement being such that the first pressure stage is produced by operation of a plunger which deforms the centre of the piston, whilst the second pressure stage is produced by the operation of a secondary plunger which displaces the piston in the ampoule.

In my co-pending application Serial No. 95,719 filed March 14, 1961 and now abandoned, I have described an ampoule for liquid medicament which is capable of being introverted to cause said medicament to be discharged and an object of the present invention is to provide an improved needleless hypodermic injector for use with such an ampoule.

According to the invention a hypodermic injector comprises a housing for supporting an ampoule in the form of an elongated shell having at its closed end a part of reduced cross section, two plungers arranged one within the other slidably mounted in said housing to engage the closed end of one of said ampoules when supported therein, the outer plunger being arranged to embrace that part of said ampoule of reduced cross section so as to give lateral support thereto, and means for driving first, said inner plunger into said reduced part of the ampoule and then both 'plungers together into the remainder of the ampoule, to cause medicament therein to be discharged in two pressure stages.

According to a further feature of the invention the means for driving said plungers comprise a spring operated mechanism mounted in a barrel concentric with said plungers and fixed to said housing.

In order that the invention may be more readily understood reference will be made to the accompanying drawings which illustrate by way of example a preferred embodiment thereof.

In the drawings:

FIG. 1 is an elevational view on an enlarged scale of an ampoule for use with the injector,

FiG. 2 is an exploded section of FIG. 1,

FIG. 3 is a section showing the ampoule after the first stage of introversion,

FIG. 4 is a section showing the ampoule after the injector has been discharged and the second stage of introversion completed,

FIG. 5 is a sectional View of an injector with the ampoule illustrated in FIG. 1 therein, the injector being shown in a loaded condition,

FIG. 6 is a sectional view on the line VlVl of FIG. 5 showing a safety latch in the locked position,

FIG. 7 is a similar view to FIG. 6 but showing the safety latch in the unlocked position,

FIG. 8 is a sectional view of the injector illustrated in 3,131,692 Patented May 5., 1964 FIG. 5 showing the parts thereof in the position they adopt after discharge of the ampoule,

FIG. 9 is a sectional view of the injector illustrated in FIG. 5, with the ampoule removed and the injector shown in the process of being loaded.

Referring to FIG. 5 the injector comprises a tubular housing 9 having a socket in one end for receiving a cylindrical ampoule. The ampoule which is shown on an enlarged scale in FIGS. 1 to 4, comprises an elongated shell 10 of thin ductile material the closed end of the shell being stepped at 12 to provide a part 13 of reduced diameter. The ampoule shell is adapted to be closed by a plug 14 having a minute discharge orifice 15, the plug being retained in the shell by a ring 16. The ampoule is a close fit in the housing 9 and is retained therein by a ferrule 19 which engages a flange 14a on the plug 14 and screws onto the housing.

Slidably mounted in the housing 9 is an outer tubular plunger 18 in which is slidably mounted an inner plunger 17 The plunger 18 is provided at its lower end with a recess which fits closely over the reduced part 13 of the ampoule and provides lateral support for said part when this is acted upon by the inner plunger 1'7. The inner plunger 17 is loaded upwardly in relation to the plunger 18 by means of a spring 21 which engages a head 17a on the upper end of the plunger 17 and a washer 22 secured on the outer plunger 13 by a circlip. The outer plunger 18 is loaded upwardly by a spring 20 which engages between the housing 9 and the washer 22.

The upper end of the housing 9 is provided with a screw thread and has secured thereto a barrel 24 enclosing a spring operated mechanism for driving the inner plunger 17 The said spring mechanism comprises a tubular guide member 25 slidable in the barrel 24 and a further tubular guide member 26 also slidable in said barrel, the two guide members 25 and 26 being arranged in telescopic relationship. Between the flanged ends of the two guide members are two springs 27 and 28 capable of being compressed into the condition shown in FIGS. 5 and 9 for forcing the two guide members 25 and 26 rapidly apart.

The said guide members 25 and 26 are retained locked together against the loading of the springs 27 and 28 by means of a ball and cone locking mechanism. This mechanism comprises a spindle 29 slidable in the guide member 25 and normally loaded upwardly therein into the position shown in FIG. 5 by means of a spring 31. The lower end of the guide member 25 is provided with a radial slot 32 in which is located a ball 33. The guide member 26 is formed with a small circumferential recess 26a in which the ball 33 seats when the injector is in the condition shown in FIG. 5, the ball being retained in said recess by means of a cone shaped extension 29a on the lower end of the spindle 29. In the position of the parts shown in FIG. 5, it will be seen that the guide members 25 and 26 are free to slide in the barrel 24, but are loaded upwardly therein by means of a light spring 34 so that if the locking mechanism is released the springs 27 and 28 react against the guide member 25 which then abuts against an inwardly directed flange on the upper end of the barrel 24.

The release of the springs 27 and 28 is effected by means of a button 35 on the upper end of the spindle 29. With the pants in the position shown in FIG. 5 depression of said button causes the spindle 29 to be displaced until the thin end of said cone shaped extension 2911 is aligned with the ball 33. In this position of the spindle 29 the ball 33 is permitted to move radially inwards and leave the recess 26a in the guide member 26, which thereupon snaps downwardly, carrying with it the inner plunger 17. This movement of the inner plunger introverts the part 13 of the ampoule in the manner shown in FIG. 3 and on the 0perative end of the plunger 17 becoming level with the end of outer plunger 18, the movement of the inner plunger is conveyed to the outer plunger by the pick-up shoulder 17 b thereon abutting the upper edge of the outer plunger 13. The movement of the two plungers 17 and 18 together causes the ampoule to be introverted in the manner shown in FIG. 4 and the contents thereof to be discharged first under high pressure as the reduced part 13 is introverted and then under less high pressure as the walls adjacent thereto are introverted within the remainder of the shell.

The discharge in two pressure stages enables first the skin to be penetrated and secondly the medicament to be injected into subcutaneous tissues at a sufiiciently reduced pressure to prevent said tissues being damaged. The use of two springs to propel the plungers has the advantage that the resonance of one spring is counterbalanced by the resonant frequency of the other, thus inequalities of pressure which cause pain during an injection are substantially prevented.

In order that the springs shall not be inadvertently released the spindle 29 is provided with a safety device in the form of a small sliding latch 36, see FIGS. 6 and 7. This latch 36 is a slidable fit in a recess in the upper end of the guide member 25 and is retained therein by a dish shaped washer 37 and spring 3 1. The spindle 29 passes through a hole 36b in the centre of the latch and is provided in the region of said hole with a reduced neck 2%, the air-angement being such that when the latch is in the position shown in FIG. 7 the spindle 29 is free to move, but when the latch is in the position shown in FIG. -8 the spindle 29 is locked.

The latch 36 is moved by the rotation of a control ring 38 and in the position shown in FIG. is loaded by a spring 39 so that the nose 36a thereon engages in notch 38a in said control ring. On rotating the control ring 38 to the release position the latch 36 is displaced and is disengaged from spindle 29. In order that the control ring 3 8 can be moved into :a positive location, there is provided a spring 41 having a detent on one end, which can be engaged in one or other of the notches 38a or 38b in the control ring.

Prior to using the injector the springs 27 and 2-8 are compressed by means of a loading device having a hollow plunger 40 shown in FIG. 9. This device simply comprises a supporting socket not shown, for receiving the housing 9 and for providing :a seat for the shoulder 9a thereon, and a lever mechanism for operating the hollow plunger 40, which is arranged to engage with the step 42 on the cap 43 at the top of the injector.

in order that the assembly comprising the guide member 25, the spindle 29, safety latch 36, cap 43 and ring 38 can be moved downwardly into the housing 24, as is necessary for loading the springs 27 and 28 as shown in FIG. 9, the inwardly directed flange at the upper end of the housing 24 is provided with a number of radial recesses 24a see FIGS. 6 and 7. For the same reason the lower edge of the ring 38 is provided with a number of outwardly directed projections 38c which are capable of passing through said recesses 24a when the ring is rotated into the locking position of the safety latch as shown in FIG. 6. In the unlocked position of the safety latch 36, the ring 3 8 is rotated into a position in which on depression of the button 35 the projections 38c abut the parts of the housing 24 between the recesses 24a so that only the spindle 29 is moved downwardly.

What I claim as my invention and desire to secure by Letters Patent is:

1. A hypodermic injector comprising a barrel, a housing secured to one end of said barrel and defining a recess for supporting an ampoule shell against lateral distention when pressure is applied to the contents of said shell, two plungers arranged one within the other slidably mounted in said housing to engage the closed end of an ampoule shell when supported therein, the outer plunger at its operative end being in advance of said inner plunger to receive a part of an ampoule shell of reduced cross-section for supporting said part against lateral distention when operated upon by the inner plunger, first and second guide members slidably mounted in said barrel between said housing at one end and flange means at the other end, each of said guide members having a flange on one end, a coil spring located in said barrel concentric with said plungers and between said flanges on said guide members, said guide members having opposed tubular parts slidable one within the other, means for retaining said guide members together to compress said spring between said flanges and means for releasing said guide members after said spring has been compressed to cause one of said guide members to drive first, said inner plunger into said reduced part of the ampoule shell until its operative end is level with that of said other plunger and then both plungers together into the remainder of the ampoule shell, to cause medicament therein to be discharged in two pressure stages.

2. A hypodermic injector according to claim 1 wherein means are provided operative after compression of said spring, to reposition both guide members in said housing.

.3. A hypodermic injector as claimed in claim 1 wherein said inner tubular part has a radial slot therein and wherein said outer tubular part has a recess therein, said means for retaining and releasing said guide means including: a ball housed in said radial slot and capable of projecting into said recess for locking said tubular parts together; a control spindle arranged to slide within the inner of said tubular parts of maintaining said ball in said recess; a manually displaceable spring operated means secured to the guide member which has the inner tubular part, said spring means loading said control spindle toward its locking position, said control spindle being provided with a substantially cone-shaped extension arranged under said spring loading of the spindle, to urge and to retain said ball into the recess in said outer tubular part.

4. A hypodermic injector as claimed in claim 1 wherein said inner tubular part has a radial slot therein and wherein said outer tubular part has a recess therein, said means for retaining and releasing said guide means including: a ball housed in said radial slot and capable of projecting into said recess "for locking said tubular parts together; a control spindle arranged to slide within the inner of said tubular parts for maintaining said ball in said recess; a manually displaceable spring operated means secured to the guide member which has the inner tubular part, said spring means loading said control spindle; a neck in said control spindle, said member with the inner tubular part having a safety latch slidable transversely therein and arranged to cooperate with said neck so as to prevent inadvertent operation of the injector.

References Cited in the file of this patent UNITED STATES PATENTS 2,671,347 Scherer Mar. 9, 1954 2,704,543 Scherer Mar. 22, 1955 2,762,370 Venditty Sept. 11, 1956 2,832,339 Sarnoff et al Apr. 29, 1958 2,940,446 Hein June 14, 1960 FOREIGN PATENTS 735,538 Great Britain Aug. 24, 1955 772,968 Great Britain Apr. 17, 1957 

1. A HYPODERMIC INJECTOR COMPRISING A BARREL, A HOUSING SECURED TO ONE END OF SAID BARREL AND DEFINING A RECESS FOR SUPPORTING AN AMPOULE SHELL AGAINST LATERAL DISTENTION WHEN PRESSURE IS APPLIED TO THE CONTENTS OF SAID SHELL, TWO PLUNGERS ARRANGED ONE WITHIN THE OTHER SLIDABLY MOUNTED IN SAID HOUSING TO ENGAGE THE CLOSED END OF AN AMPOULE SHELL WHEN SUPPORTED THEREIN, THE OUTER PLUNGER AT ITS OPERATIVE END BEING IN ADVANCE OF SAID INNER PLUNGER TO RECEIVE A PART OF AN AMPOULE SHELL OF REDUCED CROSS-SECTION FOR SUPPORTING SAID PART AGAINST LATERAL DISTENTION WHEN OPERATED UPON BY THE INNER PLUNGER, FIRST AND SECOND GUIDE MEMBERS SLIDABLY MOUNTED IN SAID BARREL BETWEEN SAID HOUSING AT ONE END AND FLANGE MEANS AT THE OTHER END, EACH OF SAID GUIDE MEMBERS HAVING A FLANGE ON ONE END, A COIL SPRING LOCATED IN SAID BARREL CONCENTRIC WITH SAID PLUNGERS AND BETWEEN SAID FLANGES ON SAID GUIDE MEMBERS, SAID GUIDE MEMBERS HAVING OPPOSED TUBULAR PARTS SLIDABLE ONE WITHIN THE OTHER, MEANS FOR RETAINING SAID GUIDE MEMBERS TOGETHER TO COMPRESS SAID SPRING BETWEEN SAID FLANGES AND MEANS FOR RELEASING SAID GUIDE MEMBERS AFTER SAID SPRING HAS BEEN COMPRESSED TO CAUSE ONE OF SAID GUIDE MEMBERS TO DRIVE FIRST, SAID INNER PLUNGER INTO SAID REDUCED PART OF THE AMPOULE SHELL UNTIL ITS OPERATIVE END IS LEVEL WITH THAT OF SAID OTHER PLUNGER AND THEN BOTH PLUNGERS TOGETHER INTO THE REMAINDER OF THE AMPOULE SHELL, TO CAUSE MEDICAMENT THEREIN TO BE DISCHARGED IN TWO PRESSURE STAGES. 